1: \(=6x^2+2x-15x-5-x^2+6x-9+4x^2+20x+25-27x^3-27x^2-9x-1\)

=-27x^3-18x^2+4x+10

2: =4x^2-1-6x^2-9x+4x+6-x^3+3x^2-3x+1+8x^3+36x^2+54x+27

=7x^3+37x^2+46x+33

5:

\(=25x^2-1-x^3-27-4x^2-16x-16-9x^2+24x-16+\left(2x-5\right)^3\)

\(=8x^3-60x^2+150-125+12x^2-x^3+8x-60\)

=7x^3-48x^2+8x-35

a. gọi phần đầu đấy là A nhá, để đỡ cần viết lại 

            A=...............

= (3x+5)² + ( 3x-5)² - 9x² -4

= (9x² +30x + 25 ) + ( 9x² -30x+ 25 ) - 9x² -4

= 9x² +30x + 25 + 9x² -30x+25-9x² -4

= 9x² + 46

sai thì thôi nhé. bạn nên kiểm tra lại

d. (2x-1)*(4x² + 2x +1 ) - 8x*( x² +1) - 5

= 8x³ -1 - 8x³ -8x-5

= -8x-6

= -2(4x+3)

sai nhé. bạn nên kiểm tra lại 

Hỏi gì mà nhiều thế

thj bài nó cần hỏi như thế lại còn bảo hỏi j mà nhiều thế

a) ( x + 2 )( x² - 2x + 4 ) - ( 18 + x³ )

= x³ + 8 - 18 - x³ = -10

b) ( 2x - y )( 4x² + 2xy + y² ) - ( 2x + y )( 4x² - 2xy + y² )

= 8x³ - y³ - ( 8x³ + y³ )

= 8x³ - y³ - 8x³ - y³ = -2y³

c) ( x - 3 )( x + 3 ) - ( x + 5 )( x - 1 )

= x² - 9 - ( x² + 4x - 5 )

= x² - 9 - x² - 4x + 5 = -4x - 4

d) ( 3x - 2 )² + ( x + 1 )² + 2( 3x - 2 )( x + 1 )

= ( 3x - 2 + x + 1 )² 

= ( 4x - 1 )² 

ôi mai dê

mấy bài này max dễ bn đăng từng phần 1 mk lm cho

Bài 2 :

a, 3(x+4)-x²-4x=3(x+4)-x(x+4)=(3-x)(x+4)

b, x²-xy+x-y=x(x-y)+(x-y)=(x+1)(x-y)

c, 4x²-25 +(2x+7)(5-2x)=(2x-5)(2x+5)-(2x+7)(2x-5)=(2x-5)(2x+5-2x-7)=(-2).(2x-5)

d, x²+4x-y²+4=x²+4x+4-y²=(x+2)²-y²=(x+2+y)(x+2-y)

e,x³-x²-x+1=x²(x-1)-(x-1)=(x²-1)(x-1)=(x-1)(x-1)(x+1)

f. x³+x²y-4x-4y=x²(x+y)-4(x+y)=(x²-4)(x+y)=(x-2)(x+2)(x+y)

a) (3x + 1)^2 - 2(3x + 1)(3x - 5) + (3x - 5)^2 

= 9x^2 + 6x + 1 - 18x^2 + 24x + 10 + 9x^2 - 30x + 25

= 36

b) (3x^2 - y)^2

= 9x^4 - 6x^2y + y^2

c) (3x + 5)^2 + (3x - 5)^2 - (3x + 2)(3x - 2)

= 9x^2 + 30x + 25 + 9x^2 - 30x + 25 - 9x^2 + 4

= 9x^2 + 54

d) 2x(2x - 1)^2 - 3x(x + 3)(x - 3) - 4x(x + 1)^2

= 8x^3 - 8x^2 + 2x - 3x^2 + 27x - 4x^3 - 8x^2 - 4x

= x^3 - 16x^2 + 25x

e) (x - 2)(x^2 + 2x + 4) - (x + 1)^2 + 3(x - 1)(x + 1)

= x^3 - 8 - x^2 - 2x - 1 + 3x^2 - 2

= x^3 + 2x^2 - 2x - 12

f) (x^4 - 5x^2 + 25)(x^2 + 5) - (2 + x^2)^2 + 3(1 + x^2)^2

= x^6 + 125 - 4 - 4x^2 - x^2 + 3 + 6x^2 + 3x^4

= x^6 + 2x^4 + 2x^2 + 124

Bài 2:

a: Ta có: \(2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\)

\(\Leftrightarrow10x-16-12x+15=12x-16+11\)

\(\Leftrightarrow-14x=-4\)

hay \(x=\dfrac{2}{7}\)

b: Ta có: \(2x\left(6x-2x^2\right)+3x^2\left(x-4\right)=8\)

\(\Leftrightarrow12x^2-4x^3+3x^3-12x^2=8\)

\(\Leftrightarrow x^3=-8\)

hay x=-2

Bài 1: 

a: Ta có: \(I=x\left(y^2-xy^2\right)+y\left(x^2y-xy+x\right)\)

\(=xy^2-x^2y^2+x^2y^2-xy^2+xy\)

\(=xy\)

=1

b: Ta có: \(K=x^2\left(y^2+xy^2+1\right)-\left(x^3+x^2+1\right)\cdot y^2\)

\(=x^2y^2+x^3y^2+x^2-x^3y^2-x^2y^2-y^2\)

\(=x^2-y^2\)

\(=\dfrac{1}{4}-\dfrac{1}{4}=0\)

Bài 1.

a)

\((x-2)(2x-1)-(2x-3)(x-1)-2\\=2x^2-x-4x+2-(2x^2-2x-3x+3)-2\\=2x^2-5x+2-(2x^2-5x+3)-2\\=2x^2-5x+2-2x^2+5x-3-2\\=(2x^2-2x^2)+(-5x+5x)+(2-3-2)\\=-3\)

b)

\(x(x+3y+1)-2y(x-1)-(y+x+1)x\\=x^2+3xy+x-2xy+2y-xy-x^2-x\\=(x^2-x^2)+(3xy-2xy-xy)+(x-x)+2y\\=2y\)

Bài 2.

a)

\((14x^3+12x^2-14x):2x=(x+2)(3x-4)\\\Leftrightarrow 14x^3:2x+12x^2:2x-14x:2x=3x^2-4x+6x-8\\ \Leftrightarrow 7x^2+6x-7=3x^2+2x-8\\\Leftrightarrow (7x^2-3x^2)+(6x-2x)+(-7+8)=0\\\Leftrightarrow 4x^2+4x+1=0\\\Leftrightarrow (2x)^2+2\cdot 2x\cdot 1+1^2=0\\\Leftrightarrow (2x+1)^2=0\\\Leftrightarrow 2x+1=0\\\Leftrightarrow 2x=-1\\\Leftrightarrow x=\frac{-1}2\)

b)

\((4x-5)(6x+1)-(8x+3)(3x-4)=15\\\Leftrightarrow 24x^2+4x-30x-5-(24x^2-32x+9x-12)=15\\\Leftrightarrow 24x^2-26x-5-(24x^2-23x-12)=15\\\Leftrightarrow 24x^2-26x-5-24x^2+23x+12=15\\\Leftrightarrow -3x+7=15\\\Leftrightarrow -3x=8\\\Leftrightarrow x=\frac{-8}3\\Toru\)